The invention relates in general to new and useful improvements in sighting devices, and more particularly to a sighting device for use on archery bows.
The bow and arrow combination has changed the course of human existence. It has provided a safer method of obtaining food, it has swung the outcome of many battles, and it has provided an enjoyable leisure time activity for those who partake in the sport of field archery.
Early humans were required to get meat at close range, attacking with knives and spears. The bow and arrow enabled the hunter to remain at a distance from his quarry so that he was less apt to become part of the hunted, thereby increasing his chances of obtaining food for those who depended on him.
The bow and arrow combination has been used as a weapon of war by many nations to defend against invaders and to offensively defeat armies on their own soil. It has helped many armies defeat forces several times as large. For example, the bow and arrow is regarded as serving an overwhelming role in the Battle of Hastings, Oct. 14, 1066, in which William of Normandy began the Norman Conquest.
Today, approximately fifty thousand years after its invention, the bow and arrow is used by over a million hunters and archers in many forms of tournament archery including Olympic events.
The bow and arrow started as a simple tool, but has evolved into a very sophisticated apparatus. An arrow generally comprises a shaft; a point attached to the front end of the shaft; a nock, or grooved piece for cooperating with the bow, attached to the rear end of the shaft; and plastic or feather fletching attached to the shaft proximate the nock. Arrow shafts are typically constructed from wood, aluminum, carbon, fiberglass, or composites of the above. Each arrow shaft material has specific characteristics regarding weight and arrow flight efficiency.
Arrow points also exist in various types. Such types include a target or field point, a blunt or roving point, a small game point, and a broadhead point. The archer chooses a point depending on the particular application, and each type of point has significantly different weight and arrow flight characteristics.
A bow typically comprises a handle, limbs and a bowstring. Sophisticated bow types are available, including long bows, recurve bows, and compound bows. The bowstring is attached to the limbs at both ends of the bow and enables the transfer of energy from the hand portion where the archer's hand draws the bowstring to the limbs of the bow. Then, when the string is released, it transfers the energy from the two limbs to the one point on the bowstring where the nock is attached. Bow strength and flexibility also correspond with arrow flight characteristics and bowstring life.
Bowstrings generally include a nockset locator to locate on the bowstring the fixed position at which the nock of each arrow engages the bowstring prior to every shot. Consistent arrow placement on the bowstring is of primary importance for achieving accuracy.
The modern bowstring is made to withstand the stress and strain placed on it by the limbs of the bow and the nock of the arrow. Nevertheless, bowstrings must be replaced and bows must be "tuned". Bow tuning refers to the process of adjusting the bow for the best performance and accuracy. Bow tuning begins with adjustments to the bowstring, fletch clearance, and nocking point. Next, the arrow must be matched to the bow to achieve good arrow flight. Finally, test shooting at close range targets and then long range targets is the final phase of bow tuning.
A majority of archers presently use bows equipped with bow sights. A bow sight, analogous to a sight on a rifle, enables the archer to more accurately orient the bow and arrow toward an intended target. Also, the use of a bow sight builds confidence and allows a novice archer to concentrate on the fundamentals of shooting. Formal target archers recognize the advantages of sights and use them extensively.
The effect of gravity on an arrow in flight is greater than the effect on a bullet traveling the same longitudinal distance because of the slower speed of the arrow. In other words, the trajectory of an arrow is much more parabolic than a bullet traveling the same distance. The trajectory of an arrow must be exaggerated when shooting at longer distance targets. Thus the distance to the target must be taken into consideration when aiming the bow and arrow. Bow sights, in order to permit accurate shooting at various distances, must be variable to accommodate the gradations in trajectory.
A common type of bow sight is adjustable to compensate for various distances from a target. The sight includes a unit that is pivotally mounted to the bow so that when the bow sight is adjusted, the sighting unit moves progressively and incrementally to compensate for the effect of gravity on the arrow. An archer judges the distance to the target, adjusts the bow sight so as to compensate for the arrow trajectory over the distance, then looks through the sight unit to the target, and shoots the bow and arrow. Although the archer is looking directly at the target through the sight unit, the bow is oriented so that the arrow is aimed to send the arrow along the appropriate parabolic path to intersect the target.
Further, the bow sight may be equipped with a gauge with various distances so that the archer need only judge the distance to the target, set the gauge to the estimated distance, look through the sight unit, and shoot the arrow.
Bow sights are accessories and are typically sold independently of the bow. Bows, as described above, come in various types and each has separate shooting characteristics. Also, the shooting characteristics of an archer varies according to the archer's height, and strength, etc. Therefore, manufacturing a gauge for a bow sight with predetermined distances for general use with various bow and arrow components to be used by various archers is most likely impossible.
Instead, a typical procedure for calibrating distances is described here. First, an archer installs a bow sight on a bow. Then the archer takes the bow to a target range, and sets the sight to an arbitrary point on the gauge. After shooting several arrows, the archer can determine (based on the distance traveled by the arrows) the precise setting for the bow sight to provide accuracy for the given distance. The archer typically places a strip of paper with an adhesive backing on the gauge, and writes or marks on the paper the distance to correspond with the distance traveled by the arrows. Thus, in the future, if the archer sets the sight to the mark on the adhesive paper and aims the bow and arrow through a sight unit, the arrow will hit a target at the distance marked on the gauge.
Once the bow is properly sighted for the first distance, the archer sights the bow for a second distance. The archer arbitrarily adjusts the sight again, shoots another set of arrows while looking through the sight, determines the distance traveled by the arrows, fine tunes the sight setting, and writes or marks on the paper to indicate the proper sight setting to ensure accuracy at the second distance. This laborious process is repeated until the archer has a suitable number of marks on the paper to correspond with various distances.
One disadvantage of this method is that use of the bow sight outdoors causes damage to the adhesive paper. The elements cause the paper to tear or wrinkle and the marks to smear. Once the adhesive becomes damaged, it must be peeled away from the gauge, and another piece of adhesive paper must be attached to the gauge and recalibrated by the laborious process described above.
The paper must also be peeled from the gauge and the gauge recalibrated if the bowstring is replaced, the bow sight or the nocking point is adjusted, or if the bow is retuned. Completely peeling the paper from the gauge is often difficult.
Another disadvantage of this method is that the paper gauge is only calibrated to correspond with distances of the arrows shot during the calibration process. As described above, different type shafts and, more importantly, different type points cause the arrow to have significantly different trajectories. Thus, the distances marked on the paper gauge only correspond with arrows having the same shafts and points used during the calibration process.
A second sighting method involves the use of small removable yardage indication stickers. Such stickers are cumbersome and difficult to place accurately. Further, with the advent of extremely high powered bows, the stickers must be placed so close together they either overlap one another or are formed with impractically small dimensions.